Has anyone tried running ducts through 3-piece crown molding or coffered ceiling?
I am trying to study my lesson before talking with some HVAC pros about ductwork. I am building a 2 story house with a central hall plan. I think a compact duct system is very do-able, because I have a walk-in closet nearby to place the air handler and the ducts won’t have very far to go to serve all the rooms. Hoping that a ducted mini split will get the job down so the air handler noise is not a problem.
What I don’t have clear in my head is the best way to route the ductwork.
Option 1…The 2nd floor will have 9 ft ceilings, so I have room to drop the ceiling in the hallway, but I’m not sure how big the ducts have to be and I don’t want to drop them down so much it detracts from the overall look of the house.
Option 2… My builder suggested creating a chase in the attic, sealing it up with spray foam and then mounding up the cellulose over top of that. My concern with this is a.) I know this option is less efficient than keeping the ductwork entirely below the ceiling, b.) the bottom of the ducts would have to sit about 12-14″ above the ceiling plane to clear a structural beam running perpendicular to the joists. And that 12-14″ is where the bottom of the ducts would be, depending on the dsize of the ducts, the top would be much higher, plus enough room to cover over top with cellulose. This means a large mound of cellulose to encapsulate below and above the duct, and c.) I also would like to have a whole-house fan mounted in the ceiling plane, and not sure if there would be room if there is a huge mound of insulation needed to cover the duct.
Option 3?? Has anyone tried hiding the ducts in a cofferred ceiling or some high-style crown molding? I see plenty of suggestions for building a soffit along the wall, but I’m not sure I like the look of a plain soffit. Those 3-piece crown moldings are really just a soffit with molding above and below, but wondered if anyone had tried to run ductwork through them. I guess it depends on how big the ducts have to be.
According to my own (and subject to error) Manual J calcs, the total upstairs cooling load is 14k, with only 4k or so needed down the hall. So hopefully that means that the ducts don’t have to be that big. And I guess another option (#4?) would be to just put a ductless head on the other end of the hall to serve the two bedrooms down there, as long as the occasionally-closed bedroom doors won’t be a problem.
I know I need to have someone do some Manual S, T & Ds to know for sure, but I’d like to know ahead of time so I can help the HVAC guys think outside the box.
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